docs: def Zigrang_Sylvester_2(Re, eD):
      r'''Calculates Darcy friction factor using the second method in
       Zigrang and Sylvester (1982) [2]_ as shown in [1]_.
  
      .. math::
          \frac{1}{\sqrt{f_f}} = -4\log\left[\frac{\epsilon}{3.7D}
          - \frac{5.02}{Re}\log A_6\right]
  
      .. math::
          A_6 = \frac{\epsilon}{3.7D} - \frac{5.02}{Re}\log A_5
  
      .. math::
          A_5 = \frac{\epsilon}{3.7D} + \frac{13}{Re}
  
      Parameters
      ----------
      Re : float
          Reynolds number, [-]
      eD : float
          Relative roughness, [-]
  
      Returns
      -------
      fd : float
          Darcy friction factor [-]
  
      Notes
      -----
      Range is 4E3 <= Re <= 1E8;  4E-5 <= eD <= 5E-2
  
      Examples
      --------
      >>> Zigrang_Sylvester_2(1E5, 1E-4)
      0.01850021312358548
  
      References
      ----------
      .. [1] Winning, H. and T. Coole. "Explicit Friction Factor Accuracy and
         Computational Efficiency for Turbulent Flow in Pipes." Flow, Turbulence
         and Combustion 90, no. 1 (January 1, 2013): 1-27.
         doi:10.1007/s10494-012-9419-7
      .. [2] 	Zigrang, D. J., and N. D. Sylvester."Explicit Approximations to the
         Solution of Colebrook's Friction Factor Equation." AIChE Journal 28,
         no. 3 (May 1, 1982): 514-15. doi:10.1002/aic.690280323.
      '''
      A5 = eD/3.7 + 13/Re
      A6 = eD/3.7 - 5.02/Re*log10(A5)
      ff = (-4*log10(eD/3.7 - 5.02/Re*log10(A6)))**-2
      return 4*ff